[Promoter methylation profile in gastric cancer]

Promoter genomic DNA methylation is an important inactivation mechanism of tumor suppressor genes. This genetic-molecular pathway for cancer may separate a subset of patients with different prognoses and eventually different responses to specific therapies.

To analyze the methylation pattern of important genes related to different carcinogenic mechanisms in patients with gastric cancer (GC) and the relationship with its morphological features and biological behavior.

Forty-seven fresh-frozen GC samples were selected. The methylation-specific PCR (MSP) test was used to analyze promoter methylation status for genes MLH1, CDKN2A (p16), APC, CDH1 (Cadherin E) and FHIT. Follow-up and complete morphological features were obtained for all cases.

We found methylation in at least one of the genes studied in 83% of the cases. The frequencies of promoter hypermethylation of MLH1, CDKN2A, APC, CDH1 and FHIT were 31%, 43%, 46%, 80% y 62%, respectively. We found a relationship between APC methylation and good histological differentiation (p =0.03); CDH1 methylation with diffuse type by Lauren and 3 or more metastasic lymph nodes (p <0.05); FHIT, CDKN2A and CDH1 methylation and female condition (p <0.04). We also found a non-significant relationship between CDKN2A methylation and better survival (p =0.07).

The high frequency promoter methylation found confirms its importance in gastric carcinogenesis. The finding of alterations in the methylation pattern of genes studied and its association with prognostic factors is a helpful tool in the search for new criteria in clinical and therapeutic decision making.